Method for recycling PMMA thermoplastic resin / fiber reinforced composite material

Abstract

The present invention provides a method for recycling a PMMA thermoplastic resin / fiber reinforced composite material, the method comprising the following steps: mixing a PMMA thermoplastic resin / fiber reinforced composite material with a solvent, i.e., methyl methacrylate (MMA), to dissolve same; and separating a solid-phase product from a liquid-phase product after the dissolution, wherein the liquid-phase product is used for preparing a PMMA thermoplastic resin or a composite material thereof. In the present invention, a closed-loop method is used to achieve the overall recovery of a resin and fibers. Therefore, the discharge of waste PMMA thermoplastic resin / fiber reinforced composite materials is reduced, and the recycling rate of the PMMA thermoplastic resin is increased, which are beneficial to environmental protection; moreover, efficient separation at a normal pressure and a relatively low temperature can be achieved, energy is saved, a device used is simple, a large-scale reaction unit or equipment is not needed, and the cost is low; and high economic and environmental benefits are obtained. PMMA thermoplastic resins and composite materials prepared by processing the PMMA thermoplastic resin and fibers that are recovered by using the method of the present invention still exhibit good mechanical properties, and have broad application prospects.

Description

A recycling method of PMMA thermoplastic resin / fiber reinforced composite material TECHNICAL FIELD

[0001] The present application belongs to the technical field of recycling of resin composite materials, and particularly relates to a recycling method of PMMA thermoplastic resin / fiber reinforced composite material. BACKGROUND

[0002] Fiber reinforced thermoplastic materials are widely used in various engineering fields due to their lightweight, high strength, corrosion resistance, acid and alkali resistance, and good mechanical and durable performance. Separating composite materials into their constituent parts is one of the main features that make thermoplastic resins and composite materials attractive, and recycling makes them truly economically and environmentally beneficial. However, the diversity and complexity of composite materials make recycling and reuse very challenging.

[0003] Currently, common recycling technologies for thermoplastic resins and composite materials include mechanical grinding, thermal decomposition of polymer matrix, and chemical dissolution. The current mechanical recycling method mainly grinds or grinds the waste resin into small particles, which is used as a filler after rough processing for reuse. This method destroys the valuable components such as carbon fibers and glass fibers in the composite material, resulting in lower performance of the regenerated material and lower added value of the recycling and reuse.

[0004] Thermal decomposition of polymers is to separate the resin and fiber material at a high temperature. Chinese invention patent CN115534259A invented a recycling system for continuous fiber reinforced thermoplastic composite materials, which produced no secondary waste, realized the recycling of composite materials and reduced the cost, but the system required a temperature of 400℃ for insulation, which had high energy consumption. H. Bel Haj Frej et al. used high-temperature decomposition method to realize the recycling of acrylic-based carbon fiber reinforced laminated composite materials (CF / Elium 188-O) (Resources, Conservation & Recycling, 2021, 173, 105705), and the composite material needed to be depolymerized at different temperatures of about 350-450℃ for more than 4 hours. The purified resin and fiber can be obtained, and the recycled fiber and resin can be reused. The thermal decomposition method can realize the recycling of composite materials, but the temperature is high and the equipment requirement is high; the high-temperature cracked resin needs to be further purified, which increases the cost.

[0005] Chemical recycling method is to use chemical solvents to degrade and dissolve the polymer matrix, and then recycle the reinforcing material. It mainly includes direct dissolution method and supercritical fluid method. Chemical recycling method can recycle fibers with better quality than mechanical or thermal recycling method, but due to the use of organic solvents, the cost is high and there is a risk of environmental pollution.

[0006] PMMA (polymethyl methacrylate) / fiber reinforced composite material maintains the strength of PMMA, and is further improved by fiber reinforcement, which can significantly improve the tensile strength, bending strength and impact strength of PMMA. It is usually lighter than traditional metal and plastic materials, which is an important advantage for applications that require weight reduction (such as automotive and aerospace fields). It has important economic significance for green recycling of PMMA (polymethyl methacrylate) / fiber reinforced composite material.

[0007] In summary, there is an urgent need for a simple process, an environmentally friendly solvent and a method to recycle PMMA and fiber reinforced composite materials to further expand the application range of PMMA. The present application provides a recycling method for PMMA thermoplastic resin / fiber reinforced composite material, which realizes the recycling of PMMA resin matrix and fiber, and is reused for the preparation of resin and fiber reinforced composite material. SUMMARY

[0008] In view of the technical problems of high energy consumption or strong pollution in the recycling process of the composite material in the prior art, the present application provides a recycling method for PMMA thermoplastic resin / fiber reinforced composite material, which does not need to be post-treated for the solvent, solves the problem of inconvenience in recycling fiber reinforced composite material, and broadens its application field.

[0009] The technical scheme adopted by the present application is as follows:

[0010] A recycling method for PMMA thermoplastic resin / fiber reinforced composite material, comprising the following steps:

[0011] (1) mixing and dissolving PMMA thermoplastic resin / fiber reinforced composite material with solvent MMA;

[0012] (2) separating the dissolved solid product from the liquid product, and the liquid product is used for preparing thermoplastic acrylic resin or its composite material.

[0013] Preferably, the fiber in the PMMA thermoplastic resin / fiber reinforced composite material in step (1) comprises one or more of basalt fiber, glass fiber, carbon fiber and aramid fiber.

[0014] Preferably, the mass ratio of PMMA thermoplastic resin / fiber reinforced composite material to solvent MMA in step (1) is 1:10-100.

[0015] Preferably, the dissolving temperature in step (1) is 30-80℃, and the time is 3-60h.

[0016] Preferably, the dissolving is carried out under stirring and / or oscillation.

[0017] Preferably, the liquid product in step (2) is added with an initiator to polymerize, to obtain a thermoplastic acrylic resin or a composite material thereof.

[0018] Preferably, the initiator is at least one of an azo initiator, a peroxide initiator or a reducing initiator, and the amount of the initiator added is 0.1-3wt% of MMA.

[0019] The azo initiator includes azobisisobutyronitrile (AIBN) or azobisisoheptyl nitrile (ABVN); the peroxide initiator is an inorganic peroxide initiator and an organic peroxide initiator, the inorganic peroxide initiator includes hydrogen peroxide, ammonium persulfate or potassium persulfate, and the organic peroxide initiator includes benzoyl peroxide (BPO), lauroyl peroxide (LPO), benzoyl tert-butyl peroxide or methyl ethyl ketone peroxide; and the reducing initiator includes N,N-dimethylaniline (DMT) or N,N-dimethyl-p-toluidine (DMA).

[0020] Preferably, the liquid product is added with a filler to prepare a corresponding PMMA thermoplastic resin composite material.

[0021] Preferably, the filler includes reinforcing fibers or nano inorganic particles, the reinforcing fibers include carbon fibers, basalt fibers, glass fibers or aramid fibers, and the nano inorganic particles include nano silicon dioxide, nano titanium dioxide or nano zinc oxide.

[0022] Preferably, the thermoplastic acrylic resin or the composite material thereof prepared by the above method is applied in the fields of aviation materials, wind power manufacturing, building materials, furniture decoration, agricultural materials, liquid crystal materials, electronic and electrical materials, optical materials, transportation, medical materials, military materials or paint coatings.

[0023] The beneficial effects of the present application are as follows:

[0024] 1. The present application realizes the overall recycling of resin and fibers in a closed loop, which not only reduces the discharge of waste PMMA thermoplastic resin / fiber reinforced composite materials, improves the recycling rate of PMMA thermoplastic resin, and is conducive to environmental protection, but also realizes efficient separation at normal pressure and relatively low temperature, saves energy, and the device is simple, without the need for large-scale reaction devices or equipment, and has low cost.

[0025] 2. Since the solvent used in the present application is an MMA reaction type solvent, MMA can be directly polymerized for the preparation of resin and composite materials, without the need for further removal of the solvent, which has high economic and environmental benefits.

[0026] 3. The recycled PMMA thermoplastic resin and fibers of the present application still exhibit excellent mechanical properties after being processed to prepare PMMA thermoplastic resin and its composite materials. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description only represent some of the embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort based on these drawings.

[0028] Figure 1 is a picture of the recycled resin and glass fiber of the glass fiber reinforced / PMMA composite material of Example 2.

[0029] Figure 2 is a picture of the basalt fiber reinforced PMMA composite material of Example 3 (Figure 2a), and the recycled basalt fiber (Figure 2b). DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments only represent some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort belong to the scope of protection of the present application.

[0031] The experimental methods used in the embodiments of the present application are conventional methods unless otherwise specified.

[0032] The materials, reagents, etc. used in the embodiments of the present application can be obtained from commercial channels unless otherwise specified.

[0033] In this embodiment, "parts" means "weight parts".

[0034] Example 1

[0035] The present embodiment provides a method for recycling PMMA / glass fiber composite material, comprising the following steps:

[0036] 2 parts of glass fiber reinforced PMMA composite material are dissolved in 40 parts of methyl methacrylate and mixed uniformly, and then placed in a constant temperature oscillator for 16 hours of oscillation dissolution at 60°C and 180 rpm. The composite material is first swelled and then dissolved.

[0037] The glass fiber and the liquid resin solution are separated by filtration, the glass fiber is washed with MMA and dried, and the recycled glass fiber and PMMA+MMA binary resin solution are obtained, as shown in Figure 1. MMA can well dissolve the waste glass fiber / PMMA composite material and can separate and recycle the glass fiber.

[0038] The recovered binary resin solution is added with a redox initiator dodecanoyl peroxide and N,N-dimethyl aniline, the amount of the initiator added is 2.0 wt% of MMA, the mass ratio of the oxidant to the reducing agent is 4:1, and the binary resin solution is continuously added with a glass fiber cloth through a vacuum infusion process, the mass ratio of the glass fiber cloth to the binary resin solution is 7:3; a PMMA / glass fiber composite material is prepared, and the tensile strength of the composite material in the 0° direction is 1121.2 MPa.

[0039] Example 2

[0040] The embodiment provides a method for recycling a PMMA resin / basalt fiber composite material, and the method comprises the following steps:

[0041] 5 parts of waste PMMA resin / basalt fiber composite material are added into 200 parts of methyl methacrylate solvent for mixing, and then placed in a constant temperature oscillator, heated to 40 DEG C, and shaken at 180 rpm for 20 hours for dissolution;

[0042] The dissolved mixture is filtered to obtain solid phase products and liquid phase products, the solid phase products are washed with methyl methacrylate, dried, and recycled to obtain basalt fibers; the washing liquid is combined with the liquid phase products as recycled resin for secondary use.

[0043] The recovered binary resin solution is added with an initiator benzoyl peroxide, the amount of the initiator added is 1.0 wt% of MMA, and a PMMA resin / carbon fiber composite material is prepared through a vacuum infusion process.

[0044] Example 3

[0045] The embodiment provides a method for recycling a PMMA resin / carbon fiber composite material, and the method comprises the following steps:

[0046] 5 parts of waste PMMA / carbon fiber composite material are added into 250 parts of methyl methacrylate solvent for mixing, and then placed in a constant temperature oscillator, heated to 65 DEG C, and shaken for 18 hours for swelling and dissolution of the composite material.

[0047] The dissolved mixture is filtered to obtain solid phase products and liquid phase products, the solid phase products are washed with methyl methacrylate, dried, and recycled to obtain carbon fibers; the washing liquid is combined with the liquid phase products as recycled resin for secondary use.

[0048] The initiator peroxylauric acid is added to the recovered binary resin solution, and the amount of the initiator added is 1.5wt% of MMA. The PMMA resin is prepared by a vacuum infusion process.

[0049] Example 4

[0050] The present embodiment provides a method for recycling PMMA resin / carbon fiber composite material, comprising the following steps:

[0051] 5 parts of waste PMMA / carbon fiber composite material are added to 250 parts of methyl methacrylate solvent and mixed uniformly, and then placed in a constant temperature oscillator, heated to 65℃ and shaken for 20h. The composite material is first swelled and then dissolved.

[0052] The dissolved mixture is filtered, and the solid phase product and the liquid phase product are obtained. The solid phase product is washed with methyl methacrylate, dried and recycled to obtain carbon fiber. The washing liquid is combined with the liquid phase product as recycled resin for secondary use.

[0053] The initiator peroxylauric acid is added to the recovered binary resin solution, and the amount of the initiator added is 1.5wt% of MMA. The PMMA resin is prepared by a vacuum infusion process.

[0054] Example 5

[0055] The present embodiment provides a method for recycling PMMA / basalt fiber composite material, comprising the following steps:

[0056] 2 parts of waste poly-methyl methacrylate / basalt fiber composite material are added to 200 parts of methyl methacrylate solvent and mixed uniformly, and then placed in a constant temperature oscillator, heated to 80℃, and shaken at 180rpm for 3h to dissolve.

[0057] The dissolved mixture is filtered, and the solid phase product and the liquid phase product are obtained. The solid phase product is washed with methyl methacrylate, dried and recycled to obtain basalt fiber. The washing liquid and the liquid phase product are combined and used as recycled resin for secondary use.

[0058] The initiator peroxylauric acid is added to the recovered binary resin solution, and the amount of the initiator added is 1.5wt% of MMA. The PMMA resin is prepared by a vacuum infusion process.

[0059] Example 6

[0060] The present embodiment provides a method for recycling PMMA / basalt fiber composite material, comprising the following steps:

[0061] 2 parts of waste PMMA / carbon fiber composite material is added to 20 parts of methyl methacrylate solvent and mixed uniformly, then placed in a constant temperature oscillator, heated to 30℃, 180 rpm, and shaken for 60 hours to dissolve;

[0062] The dissolved mixture is filtered, and the solid phase product and the liquid phase product are obtained. The solid phase product is washed with methyl methacrylate (MMA), dried, and recovered to obtain carbon fibers. The washing liquid and the liquid phase product are combined and used as recycled resin for secondary use.

[0063] An initiator azobisisheptyl nitrile and nano zinc oxide are added to the above-mentioned recycled binary resin solution, the amount of initiator added is 3wt% of MMA, and a nano zinc oxide modified PMMA resin composite material is prepared by a vacuum infusion process.

[0064] Example 7

[0065] The present embodiment provides a method for recycling PMMA / carbon fiber composite material, comprising the following steps:

[0066] 1 part of waste PMMA / carbon fiber composite material is added to 80 parts of methyl methacrylate solvent and mixed uniformly, then placed in a constant temperature oscillator, heated to 50℃, 180 rpm, and shaken for 20 hours to dissolve;

[0067] The dissolved mixture is filtered, and the solid phase product and the liquid phase product are obtained. The solid phase product is washed with methyl methacrylate (MMA), dried, and recovered to obtain carbon fibers. The washing liquid and the liquid phase product are combined and used as recycled resin for secondary use.

[0068] An initiator potassium persulfate, benzoyl peroxide and nano silicon dioxide are added to the above-mentioned recycled binary resin solution, the amount of initiator added is 0.5wt% of MMA, and a nano silicon dioxide modified PMMA resin composite material is prepared by a vacuum infusion process.

[0069] Example 8

[0070] The present embodiment provides a method for recycling PMMA resin / aramid composite material, comprising the following steps:

[0071] 5 parts of waste PMMA / aramid composite material is added to 300 parts of methyl methacrylate solvent and mixed uniformly, then placed in a constant temperature oscillator, heated to 60℃, and shaken for 20 hours to swell and then dissolve the composite material.

[0072] The dissolved mixture is filtered, and the solid phase product and the liquid phase product are obtained. The solid phase product is washed with methyl methacrylate, dried, and recovered to obtain aramid fibers. The washing liquid and the liquid phase product are combined and used as recycled resin for secondary use.

[0073] The initiator benzoyl peroxide tert-butyl ester is added to the recovered binary resin solution, the amount of the initiator is 0.8wt% of MMA, and the resin and the carbon fiber are prepared into a PMMA resin / carbon fiber composite material by a vacuum infusion process, and the mass fraction of the carbon fiber in the composite material is 50wt%.

[0074] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A recycling method of PMMA thermoplastic resin / fiber reinforced composite material, characterized by, The method comprises the following steps: (1) mixing and dissolving PMMA thermoplastic resin / fiber reinforced composite material with solvent MMA; (2) separating the dissolved solid product from the liquid product, and polymerizing the liquid product to obtain PMMA thermoplastic resin or its composite material.

2. The method of recycling PMMA thermoplastic resin / fiber reinforced composite material according to claim 1, characterized in that: The fiber in the PMMA thermoplastic resin / fiber reinforced composite material in step (1) comprises one or more of basalt fiber, glass fiber, carbon fiber and aramid fiber.

3. The method of recycling PMMA thermoplastic resin / fiber reinforced composite material according to claim 1, characterized in that: The mass ratio of PMMA thermoplastic resin / fiber reinforced composite material to solvent in step (1) is 1:10-100.

4. The method of recycling PMMA thermoplastic resin / fiber reinforced composite material according to claim 1, wherein: The dissolving temperature in step (1) is 30-80℃, and the time is 3-60h.

5. The method of recycling PMMA thermoplastic resin / fiber reinforced composite material according to claim 4, characterized in that: The dissolving is carried out under stirring and / or oscillation.

6. The method of recycling PMMA thermoplastic resin / fiber reinforced composite material according to claim 5, characterized in that: In step (2), an initiator is added to the liquid product for polymerization.

7. The method according to claim 6, wherein the PMMA thermoplastic resin / fiber reinforced composite material is a waste material. The initiator is one or more of azo initiator, peroxide initiator and reducing initiator, and the addition amount is 0.1-3wt% of MMA.

8. Process for recycling PMMA thermoplastic resin / fiber reinforced composite material according to any one of claims 1-7, characterized in that: Filler is added to the liquid product to obtain the corresponding PMMA thermoplastic resin composite material.

9. The method according to claim 8, wherein the PMMA thermoplastic resin / fiber reinforced composite material is a waste material. The filler comprises reinforcing fiber or inorganic nano-particle; the reinforcing fiber comprises carbon fiber, basalt fiber, glass fiber or aramid fiber; and the inorganic nano-particle comprises nano-silica, nano-titania or nano-zinc oxide.

10. The PMMA thermoplastic resin or its composite material prepared by the method of any one of claims 1-9 is applied in the fields of aviation materials, wind power manufacturing, building materials, furniture decoration, agricultural materials, liquid crystal materials, electronic and electrical materials, optical materials, transportation, medical materials, military materials or paint coating.

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